The water pump on one of my two 1996 Chevrolet Cavalier LS Convertibles just has failed at 168k miles. (The original pump failed at 38k miles. The AC Delco #252-779 replacement failed after 80k miles at 118k. The Airtex #AW5076 replacement pump failed 50k later at 168k miles.) Based on my research, I just ordered the following new parts for my mechanic to install:

AC Delco Professional #252-779 water pump
AC Delco/GM-OE #131-123 thermostat
AC Delco 24577118 thermostat O-ring
Fel-Pro #TCS 45972 timing cover gasket.
Cloyes #95294 timing-chain tensioner

I did not order a timing chain, guides, or sprockets because I've heard that the the original timing chains can last for 250k miles, they make noise before failing, and because many people seem to have problems after installing aftermarket timing chains. I'm not sure if it makes sense to replace the guides.

Should I replace the timing chain, and or sprockets, and/or guides?

It would be a good idea to do so, yes.