Anyone else had injector pump failure on an early cummins?

[hemirttony]

I have an early 91 3/4 ton 2wd auto. This truck does not have an intercooler. I bought it for the reputation of Cummins engines going over 500k miles with little maintenance because I commute 70 miles to work each way. I have had the truck since 98 and always got 20 mpg. A little over 2 years ago the ball bearing on the vaccum pump failed. All the balls were ground up by the gears and caught by the oil filter. After replacing the bearing and changing the oil and filter twice I was satisfied and thought this must have been a fluke problem. Now, at 285k miles the injector pump started leaking. Not a huge leak, just left a small puddle in the driveway. The next day it would not start. I cracked the injector lines to try and bleed it and got nothing. I removed the pump-(no small task) and took it to a reputable place for rebuild. After $830 I got the pump back and will be installing it tomorrow. They said the cause was rust inside the pump. I change the fuel filter every 6 months and sump it at least every month. I have never gotten any water from the sump. Is this common for these pumps to fail like this? Or is it just my truck? I always buy my fuel from the same truck stop. High volume seller so it is fresh fuel. Any other experience or advice is greatly appreciated. Thanks,
Tony