The reason very soft materials are used in bearing surfaces is to enable the bearing to trap particles down low in the bearing surface. Low enough to sit flush, so they don't continue to damage the crank pin.
The surface of the bearing itself should be something which provides a micro texture to maximize the ability to hold an oil film on it's surface. This is why so many types of racing with unlimited budgets for bearings choose to run factory honda B18C bearings (prostock, nascar, etc). Honda went through a great deal of expense to create a superior bearing surface to all other bearing types when they designed the B18C rod bearings.