\documentclass{beamer}
\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}
\usepackage[polish]{babel}
\usepackage{newtx}
\usetheme{Warsaw}


\begin{document}

\begin{frame}[t]{Krzywe B\'eziera}

\begin{tabular}{p{5cm}p{5cm}}
\includegraphics<+->[scale=0.9]{bezier1.pdf}&
\includegraphics<+->[scale=0.9]{bezier2.pdf}\\
\includegraphics<+->[scale=0.9]{bezier3.pdf}&
\includegraphics<+->[scale=0.9]{bezier4.pdf}
\end{tabular}
\end{frame}

\end{document}