Curious.........
I didn't know it was a 2000 however it may have the ACE system.
also check your pulleys, they're plastic and when they wear though they make noises, may want to check your belt too. It does sound to me like it has something to do with the pump. What is the color of the fluid look like ? Dirty and dark, or the color of the fluid you use ? What fluid are you using ? It could be that the pump is faulty, If this system doesn't have the ACE system, is there still a power steering filter?
About the power streeing pump, I'm not sure on the design of the pump, weather it is a card type or eccentric, but this makes little to no difference. the way Landrover put it in it's a joy to remove. You'll have to remove the A/C unit and lay it off to the drivers side. the front pulley comes off then the whole mounting bracket that holds the pump and A/C to the head comes off. All because they use a stud with different thread sizes on each end for the center power steering pump support stud.
I'd would tend to agree with you that it is the pump, and if the fluid is getting dirty, the sooner it is replaced the better.
Let me know If I can be of further help...........
best wishes.................... chongo