1991 Jeep Cherokee 4L water pump

Think of it as you would in your house when a breaker trips. You have a short and what is causing the short? How do you find it? I start checking components on the circuit to find one that shows signs of problems. I might unplug one component at a time to find the one that trips the breaker or blows the fuse.

You don't specify whether your enginge is a V6 or Inline6, BUT.
I recently replaced the water pump an my 96 Inline6 Cherokee Country, did not require removing radiator, just removing the radiator fan shroud and serpentine belt to gain fairly easy access to the water pump & engine cooling fan (4 Nuts)/pulley assembly. I didn't have to loosen/set aside any other components. Removal and reinstallation was actually very easy and can definitely be done by the avg. Shade tree mechanic.
As far as making sure the work isn't wasted, you ARE sure that the water pump is bad? There is a "weep hole" on the bottom of the "nose" that sticks out from the water pump body torwards the radiator. If the internal pump seal is going out you will see fluid leaking out from this area onto the ground, unless it's been covered over with grease/dirt. Crawl under the front of the engine compatment and look with a flashlight - it may be hard to see the hole, but it IS there. If the water pump bearings go out, you'll hear a squealing sound coming from that area. It can be checked without removing the pump - loosen the drive belt, then try to rock the pump pulley up/down/side-to-side/forward/backwards. If you have noticable movement, safer to replace pump, they're not that expensive. HOWEVER, the squealing sound could ALSO be caused by a loose drive belt. The water pump on my 96 uses the SMOOTH side of the serpentine belt and does require occasional "tightening" to take the slack out - rubber belted will slightly stretch with wear, even new one. Need more info, post back. Also recommend getting at least a HAYNES repair manual for your year model from your local auto parts store, has photos and instructions, and will answer lots of questions that may come up ('84 - '99 Cherokee, Book #50010) if I remember correctly. Good Luck.