At first you don't see the metal iron particles. The next fase is, that the metal corrodes and gives the rust spots.
It is almost impossible te remove the rust specks with a polishing cleaner. You have to remove the oxide layer first with oxalic acid. And if the oxidised iron layer is removed, you can then remove the small iron particle.
Be carefull with oxalic acid. Let the solution work for about 15 minutes. Then rinsing with fresh water to remove the metals particles and to remove the acid.
Then you can clean the surface and give it a wax treatment.
These rust problems are very common. Be carefull when a neighbour with a steel hull
starts grinding on his boat.