The last 2 times it has quit working, it has done it while driving, it'll be running just fine, then just stop. Would a poor quality pump cause this as well?

 

Like stated above... Aftermarket pumps made for GMs are junk. The pump is overheating and stopping. You will need a new pump. The AC Delco pump is around $400 IIRC. But you wont have to replace it for a few years at least.