First thing I'd check is WHY does it have a new water pump......A new water pump isn't a big deal, but if they replaced it after the old one went out and the Jeep overheated and might have blown a head gasket or cracked a head or simply still gets hot even after the new water pump then it's a definite NO-GO for me. The Alternator isn't a big deal at all, but with something like a water pump that can completely ruin the engine I'd be highly concerned with that.
Take it for a drive (at least 15-20 miles and make sure you crank the A/C up all the way and stop and idle for at least 10 minutes) and run that son of a gun like you stole it for the majority of those miles. If it makes it with no issues whatsoever, then great it sounds like you might have gotten a pretty decent deal on a good WJ....If it gives you an engine light or gets hot or has anything else you are concerned with then pass on it.
In my case, I just bought (like 2 weeks ago) an '04 WJ Limited with a V8....When I started it everything in the jeep worked with the lone exception of an engine light. It was a transmission code that I eventually got fixed for nothing (brand new Torque converter because I made them show me the bill) and not one but 2 full tranny services (with flush and new filter each time according to the bill from the tranny shop). What I have now is an '04 WJ Limited 4.7V8 4x4 quadra-drive with almost all the bells and whistles including leather and sunroof and it runs perfectly now for less than $4500. Taking into account what I would have had to spend getting the TC replaced at a shop I figure I'm in about $3000-3500 in on this. Yes I will need to get 4 new all terrain tires for it but honestly I wanted to buy new tires anyway just so I could get what I want.
The point is, don't buy this Jeep you're looking at unless you are completely comfortable with it. Test drive it twice as hard as you'll ever drive it.....if it breaks then what are they going to do? FORCE you to buy it?
Also, as someone with a WJ with an I6 and a WJ with a 4.7 V8.....The difference is definantly there. The V8 is definantly more powerful but IMO personally I preferred the I6. Keep in mind though that I've only had my V8 WJ for about 2 weeks now.....I'm still very used to the engine noises and maintenance schedule on my I6. Good luck and I hope you find a perfect WJ for yourself!