Water Pump and Alternator questions

[Carrerax]

Hi all, I have a 2001 X5 4.4 with 115k miles. I had a friend that just had his waterpump go and take the radiator and many other things with it. He had 130k. I have owned this for a long time and it will be my wifes car for several more years. Im now scared that my water pump is going to do the same thing so I intend on replacing it myself in a week or two.

Question is, I have read that the Alternators also go about this same mileage. I dont have a ton of cash and would rather just do the WP but does it make sence to do them both now or just wait till the Alt goes and then replace it. since I am in there it seems it would be much easier to do them both now but if the alternator will last until 150k I dont want to spend the money. Please give me your opinions.

Also, I am mechanical and will not be paying to have it done. TIA, Mark