Life of my Water Pump
The life of my water pump was 170K, but I don't know the early service history as it concerns antifreeze replacements and what brands were used. I did change MB antifreeze at about 150K and it looked like the color of normal MB fluid at that time.
I suspect that another important variable would be the serpentine belt tension, and perhaps more important yet would be the belt shock absorber and its upper and lower rubber bushings. If all of these are kept in good order I suspect that the resultant lack of vibration might help WP bushing and seal to last longer. Any noise or movement in the shock-tensioner mechanism at idling speed would be an alert to check for bushing and or shock wear.
Luck with your latest repairs,