Catalysis of the reaction: 1L-1-O-(indol-3-yl)acetyl-myo-inositol + UDP-L-arabinose = (indol-3-yl)acetyl-myo-inositol 3-L-arabinoside + H+ + UDP.
UDP-L-arabinose:(indol-3-yl)acetyl-myo-inositol L-arabinosyltransferase activity