If we have a steady isothermal incompressible flow (with non-zero velocity field), the density must be constant and uniform, right?

If yes, can we conclude that the number of fluid elements(very tiny fluid particles, from which the flow is made of) in the(per) unit volume is the same? To rephrase it, is the number of fluid particles in the area where the flow is very slow and the area with higher velocity (per unit volume) same?