I think water pump life varies greatly depending on several things. As an example, BMW's are notorious for water pump failure. Mine went at 50K. On the other hand, my wife's Mercedes 190D was 18 years old when we sold it and never had a single problem with the cooling system.
I believe that using tap water is the cause of a lot of failures in cooling systems. Another reason is failure to maintain fresh coolant in the system for lubrication.
BTW, 600CDN seems like a lot of money for that work.