Rune Socket suggestion for high ES Advanced Robe

Hey all. Newish to the game and Im finally realizing you cant build full damage as a Cold/Lightning Monk so Im investing in ES. I feel like I got a really good Robe roll for ES, but Im wondering if I should use elemental resistance runes for the sockets, or go full ES and use Iron Runes for the extra ES.

Any advice is appreciated, thank you!