1. For people good at what they do, promotion can come with higher pay and a new title prefix, but the tasks associated with the position stay the same. So there is 'assistant' plumber, 'associate' plumber, and 'senior' plumber, 'grand master' plumber, etc.
2. For people who are bad, they don't get a promotion, but a job change. So their prefix stays the same, as does their pay, but now they are the 'assistant' professor.
This solution keeps the math the same as in the Peter principle version above, but doesn't have the same economic consequences of 'promoting' the worst performers.