Correct me if I'm wrong, but it looks like you are using a 90gph, 5 micron filter, on a pump that flows 140gph and needs a minimum of a 40 micron pre-filter. It also looks like it's in a spot that gets wet on a regular basis.
http://www.jegs.com/p/Fram-Autolite/...45053/10002/-1
If this is indeed the filter you are using, your new pump will suffer the same fate.