I'd of thought it must be a belt noise, if you open the bonnet when its hot can you trace it that way ?? ie try the steering when stationary to see if it makes the noise worse.

Not sure if the water pump etc would make that noise if the bearing was on the way out ??

After a run put the lights & heater on etc & see if the noise changes tone, that might narrow it down to either the belts or something the belts a running.