This is Andrew - I started this discussion and am responding to the comments by Benny and Roger.
Benny, I mispoke myself in describing the separation of the hub rim from the barral of the hub, so your comment is very well placed. To re-describe it, the location of the fatigue and separation was at the weld between the flat circular portion of the hub unit that holds the lugs and the barral of the hub unit that holds the bearings. As I think about it in response to your commentary, as you properly mentioned the lugs did in fact go all the way through but the whole portion that holds the lugs and wheel is what separated and allowed the wheel to go bounding off through the woods. Now I'm wishing that I had the broken hub and it's mate so that I could have a detailed look at it to more accurately check its construction and post a photo. So thanks for your comment that clarifies the situation.
In any case, I still think that anyone who does not have cast iron hubs should inspect carefully and consider replacement.
Roger, again I wish I had those hubs that I replaced so that I could check for a manufacturer's name. At this point I have just the axle
with the replacement hubs on and no identification possibility. Good suggestion and I'm sorry I can't give an accurate response.