How to replace Bouillon cubes without making them on my own
The examples you gave - pasta and rice - are presumably using boullion cubes and water. The cubes are basically supposed to be dehydrated broth, so you can just use whatever kind of stock or you prefer instead of the water. Often boullion cubes are saltier and have more umami than the stock they'd replace, so you may find you want to add back in some salt and some other source of umami (MSG or a more substantial ingredient), especially if you're using vegetable broth.

Depending on what your objection to bouillon cubes is, you might also like a vegetable stock base (Better Than Bouillon is a common brand). It's basically the same thing as the cubes, except in paste form.

But in any case, the bouillon is basically stock (minus water) so you should look to stocks for your substitutions. The primary two concerns will be salt and umami, but you probably are benefiting from some more subtle flavors too - and even if the bouillon cubes are lacking in that department, a good flavorful stock will be a welcome improvement.