I hear ya...but it's very rare that a water pump will leave you stranded... more often then not that's because someone was ignoring the leak and then it finally gives out.

Alternators and starters are just as common of a failure as the water pump that could leave you stranded. Hell, even the power steering pump can fail and leave you stranded if it seizes and ruins the belt. I know these parts are a bit more money than a water pump, just pointing out that there's quite a few other things that are replaceable as well if you really want to replace parts before you have an issue. There usually aren't any warning signs with the alternators go.... just that battery light comes on and you run out of juice.