... and using the  /r substitution modifier of 5.14+: 

>perl -wMstrict -le
"printf qq{'$_' } for glob('ferber' =~ s{e}{{e,a}}xmsgr);
"
'ferber' 'ferbar' 'farber' 'farbar'

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In reply to Re^2: Substitution of a particular letter in all combinations of positions in word (see inside) by AnomalousMonk
in thread Substitution of a particular letter in all combinations of positions in word (see inside) by Doctrin

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