Yo, I'm sorry but I'm having a hard time believing that just not changing the antifreeze ate that pump like that? Almost 100% of cooling systems in 1999 where 5yr 100,000 mile coolant change intervals. I'm not saying I personally would wait that long, but good for that never-the-less. I think something is up, you mentioned you have had the car a year, so you bought it used... Who knows what idiot or idiots that owned/serviced/jiffy lubed the car before you, and what they put in there. I bought my 2000 Max brand new and still running it, and have only changed my antifreeze once, and even then it didn't need it, still looks new now and that change was over 3yrs ago. My 2 cents.

 

You might be on to something. I tend to change everything that is to change every time I get a used car, because of that very same reason; who knows what the previous owner did/did not. So I should know better than neglect that crucial part. It's not like neglecting to put windshield washer fluid in its reservoir. It could've been worse, though, if I blew a head gasket or something else due to overheating.
All I can say is, lesson learned.