A liner hanger has slips held by a slip body. A potential energy force to move the slips axially when the hanger is in position is selectively released. The nature of the loading between the slips and the casing changes from a radial reaction force from the casing going into the slip and then distributed circumferentially to the slip housing to an essentially axial loading of the slip housing down onto the slip that has penetrated the casing with an opposite reaction force in the casing wall. The contact location between the slip housing and the slip is made broader at the slip end with a wider portion having an undercut to reduce contact stress and to aid in promoting flow past the set slip. The slip housing also has axial flow channels that interact with the undercut to promote flow past the set slips.