My W124 steering wheel has worn to that point as well.
I have a steering wheel cover as a stop gap measure until I can procure ($$$) for a new leather and wood steering wheel. That is about all you can do.
Unfortunately, I am using one of the $10 simulated burlwood/knobby vinyl covers right now, and it is as cheesy as it gets!
But the priority right now is being able to grasp the wheel without bits of MB material coming off my hands! So I will live with this tasteless solution until I have the means to procure a nice $700 steering wheel...