1994 Jeep Cherokee you can hear my truck a block or so away

I was wondering about a cherp bird sound comming from under my hood I have been told my water pump and also been told my belts I have been driving the car around with the annoying noise for months cause of lack of cash. The sound is always there but the pitch changes every day latly it sounds really bad every time I start and drive it im taking it in tomarrow for a water pump but I dont get how it can be the water pump I have water in the overflow and it has been driven around for months like this shouldent it have siezed the engine from driving this long like that if it was the water pump? I replaced the water pump and belts about 2 years ago if not less. The car does not have any smoke or steam comming off it. I dont think it is over heating but I guess I could be wrong im just wondering if I maybe getting ripped off 250 to replace the water pump tomarrow? Thanks for your time its a great site.