1 Mark USA
2 Amir UK
3 Pant USA
4 Veer IND

657890
768908
435678
342343

1 Mark 657890 USA
2 Amir 768908 UK
3 Pant 435678 USA
4 Veer 342343 IND

1 Mark USA
2 Amir UK
3 Pant USA
4 Veer IND

657890
768908
435678
342343

z=`awk '{print NR}' file1| sed -n '$p'`
for ((i=1;i<=$z;i++)); do j=`sed -n ''$i'p' file2`;  awk -v i="$i" -v j="$j" 'NR==i{$4=$3;$3=j;print $0}' file1; done

1 Mark 657890 USA
2 Amir 768908 UK
3 Pant 435678 USA
4 Veer 342343 IND