Presuming you mean to take the newline-delimited names and treat them as input to the inplace-edit process, I think this will do (untested, as I'm not on windows, and I may get the quoting wrong):

dir /b/S | perl -pe "BEGIN { chomp(@ARGV = <STDIN>) } s#\bGPP\b#Arjun#
+i;" -i.bak
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-- Randal L. Schwartz, Perl hacker
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