A chemical mechanical polishing composition, including, as initial components: water; an abrasive; an inorganic salt of an alkali metal or an ammonium salt or mixtures thereof; a benzyltrialkyl quaternary ammonium compound having formula (I): wherein R1, R2 and R3 are each independently chosen from a (C1-C4)alky group; an anion; and, a hydroxyl-containing quaternary ammonium compound having formula (II): wherein R4, R5, R6 is each independently chosen from H and an alkyl group; wherein R7 is an alkylene group; and anions. Also disclosed are methods for polishing a substrate with the chemical mechanical polishing composition.