The clearances are more open. Parts have blunt rather than tapered edges. The metal parts are harder. Some designs are rubber lined to absorb the impact of abrasive fluids. They are less efficient than chemical pumps.
Many slurries are dilatants.
Their viscosity increases with agitation. You may have to convert to a positive displacement design. Kaoline or china clay is a good example. Some sugar syrups fall into this category also. Multistage vertical and horizontal pumps are another option.