What's the cause of the scars on these cherries?
Are they coming from a disease?


No, this appears to be a combination of rain damage and pests. If a disease were present, much more of the cherry would suffer, there would be signs of rotting, and, the damage wouldn't solely be so superficial, as is the case in your posted images. 

Consider the next few images which demonstrate the effects that various diseases have on a cherry, and notice how much more detrimental [and different] the impact.

Bitter Rot (Colletrotrichum gloeosporioides &amp; C. acutatum)


Brown Rot (Monolinia fructicola)


Alternaria Rot (Alternaria sp.)


There are other [equally common] diseases of cherry trees (Prunus sp.), including cherry spot leaf, black knot, silver leaf, and PNRSV, however, in pretty much all of these cases too, there's no modification to the cherry fruit (excluding extreme circumstances, as is the case with spot leaf, I believe).

Instead, as mentioned, one major cause of the damage is rain. Just before harvest, when the cherry is at it's greatest [and possibly maximum] volume, rain that's absorbed through the surface of the cherry causes the cherry to further enlarge, which ultimately splits the cuticle (skin). The result is the following:

   

    

For more information on cherry splitting/cracking: 


Fruit Splitting (Cracking) – What causes it and can we do anything about it?
Fruit Split In Cherries: Learn Why Cherry Fruits Split Open
A Review of Cherry Fruit Cracking
Story: Stone fruit and the summerfruit industry
Cherry Weather Worries




Given the irregularities of scarring on some of the cherries, I also suggest that insects and/or birds scratched/ate away at them. Consider the following images that illustrate the kind of damage that birds &amp; wasps cause when feeding on cherries, and notice the similarities to those in your images.

bird damage


wasp damage


This, in combination with the rain, is most likely what caused damage to your cherries.




  Is it correct to call them "Cherry scabs"?


I just call it scarring, and I believe many other people do too. I'm not sure if there's a specific term for fruit damage that's then been "scabbed" over. If someone knows of a term for this, please provide in a comment and I will supplement my response with it. Thank you.



While continuing to research this topic, specifically when attempting to find alternative reasons that could explain this kind of damage, I did ran across this article which talks about wind damage, and provides an image that slightly resembles the markings on your cherries. I'm still heavily convinced though that your cherries suffered their damage from rain &amp; pests.