How is the water pump bearing lubricated?
By the antifreeze in the coolant.
That is one of the reasons there is a change interval for the coolant, the coolants anti-freeze properties don’t wear out but the additives do.
I remember when most cars on the road had a grease fitting on the water pump and you had to measure of alcohol in your radiator once a week in the cold weather.
Of course I also remember the lamplighter coming down the street to light the gas streetlights every evening, so I guess it is possible I am getting old. When I was still driving a school bus I came into our break room and there were about 25 drivers waiting to punch out and I said something about getting old. Like a rehearsed chorus they all said " What do you mean GETTING !"
The bearing in the water pump is a sealed bearing, it is outside of the coolant/water pump seal. The weep hole is located between the water pump seal and the bearing, it protects the grease in the bearing form coolant contamination.