In a two phase pipeline made of carbon steel, you would experience erosion due to droplet impingement at any change of direction or at any protrusions into the flow stream, such as the root beads of welds that are not completely flush with the ID of the pipe.  The only place within the oil industry where this level of velocity can be regularly found are at chokes.  These are basically pressure reduction orifices and the restriction orifice is generally made from a material such as tungsten carbide or a hardfacing material such as stellite.

As for the erosion, the severity of the attack is a dependent upon the velocity, the mass of the droplets and the difference in density of the liquid and the gas.