Most failures I have read about are related to guess what, poor electronics in the pump itself. BMW seems to have a long standing issue with issues related to this in all their models. Seems like if they would beef up that issue by making their suppliers meet higher reliability standards we would all benefit.
I am probably not far away from needing to replace mine and I am actually looking to buy one if I can source a good price and keep it in the car just in case.
Oh well goes with owning a car like ours. If you think about it an electric water pump is a much better idea so it can run hard in stop and go traffic and easy on the interstate. Good idea but implementation related to electrical reliability needs some work...