I replaced the pump on my '91 myself; it seems like one of the easier water pumps to replace, as water pumps go anyhow. Not sure about the '93 in comparison to the '91.
A few tips (I assume you're familiar with doing routine stuff like changing the coolant, etc., and also assume you have a manual showing the basics on how to do this job):
- Use a new GM pump. They cost 2x as much as other pumps, but they are worth it for how long they last. Even if some other brand offers a really nice warranty, go with the GM part; remember that you are the one that gets to replace the thing again if it goes bad
My GM replacement pump has over 60k miles on it now and is showing no signs of problems.
- You will have to clean *all* of the old pump gasket material off of the timing cover (the pump mounts on the front of the timing chain cover). The timing cover is aluminum and thus easy to damage. This is the most time consuming part of the job. I think NAPA sells a gasket remover that works well but MUST be carefully & sparingly used (don't get any of it in the cooling system) and then *thoroughly* washed off.
- I always use distilled water instead of tap water to mix w/ the antifreeze when refilling the cooling system.
- Torque the bolts on properly when installing the new pump.
- The bigger bolts on the water pump I believe will need thread sealer (note: not thread locker).