Unfortunately your engine may be on borrowed time. The coolant passages in the heads can be very small, and bits of plastic from the pump could well get lodged there, leading to local hot spots and eventual cracking.
Too late for you, but that's why I chose to be pro-active and replace my 10-year old pump before it self-destructed.
Best of luck, man! (If you engine does go pop, think of it as a good excuse to go for a Raby rebuild.)