You’re just rubbing sand in it

I heard this one by Willie Geist on the Today show.  He meant to say “you’re just rubbing salt in the wound” as he was explaining that the person’s actions were making the situation worse.  As for the other expression, not sure but certainly sand is abrasive and can hurt if in a wound.  It also conjures up in my mind the guy kicking sand in the other’s face, aggravating the situation.