I have seen this, but have yet to try it. I know that some recipes will incorporate vegetable juices in them to add flavor and color. Let me know how it turns out if you try it. I would assume that you could replace all the liquid with pesto because it contains oil.
On a similar note... I like to make garlic pasta and basil pasta, cook the two together, and add parmesan and a dash of good olive oil to the result. Pesto flavour, and the texture of the cheese is not lost.
Yes you can incorporate pesto into pasta. You can incorporate pesto into almost anything, cakes, brownies, chilli, soup, rice, all your mother sauces, LOL, of course you gotta use your judgement. You can also incorporate almost anything into pasta!
On a more serious note, the answer is a resounding YES! You can incorporate pesto into your pasta. Bear in mind that the protein structure will be compromised with the addition of the oil. And no, oil is not a substitute for water in pasta dough. The starch granules cannot hydrate if you do not have any moisture.
You can add lots of stuff to pasta.
We add whole grain mustard, or infuse saffron in the liquid before making and I quite like adding sun-dried tomato paste. Adding spinach to make green pasta and squid ink to make it black should be well known. One I tried that I don't recommend is chocolate pasta.