The original pump on the '89 Bonneville we had in 1995 failed at 120k miles 60 miles east of Great Falls, Montana, in November at dusk. I had picked one up along with a set of tools the night before because I thought it was making too much noise for comfort. Took about 45 minutes changing it beside the road, somebody stopped to help and got water from a near-by house for me to add enough to make it to GF, told me where to leave the water can after we got back on the road.
Same pump was still on the car when it was totalled at 170k in 1997.
About the only thing easier to change is the alternator.