Okay, I'm a lucky one. I got over 8 seasons (years actually) on my original bone stock pump. 518 hours to be exact. I was EXTREMELY lucky when it did finally let go. I had just launched off the trailer when it failed. During my routine checks after start-up I noticed the water temp coming off the peg a LOT sooner than normal, especially considering the cold water I was in (Willow Beach, Lake Mohave). I looked over the back and noticed no water coming out the pipes. Yikes. Quickly docked and shut her down. No over heat, no damage except the pump. I did have a new spare pump I had just purchased for such a situation. If I was smarter I would have swapped pumps prior to this trip.
Despite the fact the pump changed out relatively easily (took about 45-60 minutes on the trailer), when I got home I had to back flush every hose I could find that was 'south' of the thermostat housing. I found one large piece in the power steering cooler and another in the thermostat housing itself. It had lodged in the thermostat at one point not allowing it to close. Engine had a tough time maintaing temperature.
I'm not so sure I'll be as lucky next time.