Last year I found some indicators by an outfit out of Maple Ridge called Top Shelf floats - they have a hard-ish rubber insert in the middle and a hollow plastic peg that secures the line in same manner as the Rowley style indicator. They aren't cheap, but I've been using the same one for more than a season now and it's still going strong and doesn't have the issue of the leader wearing groves in the foam of the indicator body.