Does this wiring for the addition of a switch to bypass the PIR look correct?
So your proposed wiring scheme looks great when it's in PIR mode.  

However, throw the switch to "other thing" mode, and what do you see?  


The PIR's supply wire is disconnected. 
The PIR's lamp-side wire is being back-fed with hot.  Is that good for it?  Does its instructions say that's alright?  


The other problem with PIRs is you really want to power them 24x7.  They also have light sensors, and they need 24 hours to see the maximum and minimum absolute lux in the location, so they can distinguish night from day in adverse conditions.  

So I would flip it around.  I would make sure that PIR supply (brown) always sees hot, and PIR neutral (blue) always sees neutral.  I would run PIR switched-hot to one side of the switch, and always-hot to the other side of the switch.  The pump goes to the common. 

Now the PIR is always up, but it either has a load, or does not.